In the technology of long term evolution (Long Term Evolution, LTE), transmitting a positioning reference signal (Positioning Reference Signal, PRS) is proposed to implement a positioning technology of observation time difference of arrival (Observation Time Difference of Arrival, OTDOA), and its application architecture is shown as in FIG. 1. An OTDOA positioning system includes three kinds of devices which are a base station, a terminal and a network side positioning server. The OTDOA positioning technology is a positioning method assisted by a terminal, namely, the terminal performs measurement of a reference signal arrival time difference (Reference Signal Time Difference, RSTD), and the network side positioning server estimates a position of a UE according to the RSTD measurement result.
Multiple base stations transmit positioning reference signal subframes (Positioning Reference Signal Subframe) for terminal positioning. This time interval is called a PRS measurement occasion, one PRS measurement occasion includes one or more positioning reference signal subframes (Positioning Reference Signal Subframe).
The network side positioning server transmits a measuring assisting message to notify the terminal of configuration for each base station to transmit the positioning reference signal subframes.
According to the assisting message, the terminal receives downlink subframe signals transmitted by each base station in the PRS measurement occasion, measures a PRS reference signal arrival time difference (Reference Signal Time Difference, RSTD) of the PRS subframes transmitted by each base station and reports to the network side. The network side performs a hyperbolic positioning according to the RSTD, and obtains an estimated position of the terminal.
Through measurement, the PRS received by the UE is correlated with a local PRS, and the RSTD is obtained according to the location of a correlation peak. Whether a correct location of the correlation peak can be obtained is impacted by an autocorrelation characteristic of the PRS, and the impact increases as the number of the PRS within the positioning reference signal subframe increases, and also increases as the number of the positioning reference signal subframe increases. Therefore, the detection probability of the RSTD measurement is limited by the number of PRS reference signal symbols available for measurement within a subframe. However, the PRS is a newly introduced reference signal in R9, the protocol stipulates that the positioning reference signal should be compatible with R8 design. The PRS cannot be transmitted on symbols occupied by cell-specific reference signals (Cell-Specific Reference Signal, CRS). The number of the reference signal symbols available for measurement is limited, and thereby the detection probability of the RSTD measurement is constrained.